1. Field of the Invention
This invention relates to a method for manufacturing foam pads, particularly to one able to form air bubbles communicating with one another successively in the interior of a shaped foam pad so that the foam pad has an excellent effect of fatigue resistance.
2. Description of the Prior Art
Articles made of foam pads have been widely used either in people's livelihood or in sports. Generally, a conventional method for manufacturing foam pads includes the following steps: Firstly, a proper amount of polyvinyl chloride (PVC) powder, dioctyl phthalate (DOP) curing agent, light calcium carbonate, kaolin, foaming agent and pigment are blended together. Secondly, the mixture of the materials is compressed and coated on a conveyer belt or on separable paper by rollers and then heated and foamed in shape at high temperature. Lastly, the foam pad shaped is thermo-compressed in a mold and then cut into foam pad finished products.
However, although various foam pad products can be produced by the conventional method as described above, yet the air bubbles formed in the interior of the foam pad are respectively a closed air bubble not communicating with one another. Therefore, when such a foam pad is compressed, the individual air bubble being compressed will immediately produce a rebounding force. Under the circumstances, although the foam pad has buffer elasticity, its rebounding or buffering force is comparatively strong; therefore, some products made of such foam pads, such as shoe pads, sports pads or the like, may make a user feel uncomfortable at his foot or at a certain part where is compressed by the foam pad, and even may cause aching in muscles in case of using the foam pad product for a long period of time.